The Federal Motor Carrier Safety Administration (FMCSA) requires that an active and valid U.S. Department of Transportation (USDOT) identification number must be properly displayed on commercial motor vehicles. The USDOT's regulations mandate that companies that operate commercial vehicles transporting passengers or hauling cargo in interstate commerce must be registered with the FMCSA and must have a USDOT number. The information to be displayed on both sides of the vehicle consists of (a) the legal name or a single trade name of the motor carrier operator and (b) the operator's motor carrier identification number preceded by the letters “USDOT”. A violation of the vehicle identification requirements can result in a fine of as much as, for example, $11,000.
A number of transportation management companies are interested in automated camera-based recognition of USDOT numbers, wherein a camera is installed on the side of the road and triggered by an in-road sensor to capture an NIR/RGB image of an incoming truck. The captured image is then processed to first localize and then recognize the USDOT number on the side of the vehicle.
Currently, techniques are in operation, which automatically recognize USDOT numbers from vehicle side images captured by an NIR camera. FIG. 1, for example, illustrates a sample prior art image 10 of a side vehicle captured by a camera. The image 10 shown in FIG. 1 is a sample of the image of the side of a truck. The particular image 10 depicted in FIG. 1 not only contains the US DOT number at the bottom of the truck door, but the vehicle identification number in the center and the name of the trucking company above that. Other trucks may contain additional information such as the weight of the truck and the location of the trucking company. A full image of the truck may also contain text in the form of marketing signage, and information that identifies the function of the truck. An algorithm to identify the tag number must be robust against the presence of all this additional information.
FIG. 2 illustrates example prior art USDOT number images 20 having a variety of fonts and image quality. The USDOT number can be written with a variety fonts and sizes on the side of the truck. This variation, in addition to other source of noises, low contrast, and illumination variation poses a challenge on the recognition accuracy. FIG. 2 thus depicts examples of localized USDOT number images with a variety of fonts and sizes. Some of these images are very noisy since captures of the side of the truck are not always performed under optimal conditions. Imaging at night in ongoing traffic might require an NIR camera with low exposure time causing images to be noisy and low contrast. There are also other variations that mitigate the recognition performance such as dark on light or light on dark, embossing, glare, extra characters, blur, etc. All these variations in turn have a negative impact on the recognition accuracy.